s908ey8ad4cfjer Freescale Semiconductor, Inc, s908ey8ad4cfjer Datasheet - Page 163

• Manufacturer Part Number: s908ey8ad4cfjer
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

If more than one interrupt is pending at the end of an instruction execution, the highest priority interrupt is
serviced first.
is pending upon exit from the original interrupt service routine, the pending interrupt is serviced before the
load-accumulator- from-memory (LDA) instruction is executed.
The LDA opcode is prefetched by both the INT1 and INT2 RTI instructions. However, in the case of the
INT1 RTI prefetch, this is a redundant operation.
14.5.1.2 SWI Instruction
The SWI instruction is a non-maskable instruction that causes an interrupt regardless of the state of the
interrupt mask (I bit) in the condition code register.
14.5.2 Reset
All reset sources always have higher priority than interrupts and cannot be arbitrated.
Freescale Semiconductor
Figure 14-10
To maintain compatibility with the M6805, M146805, and MC68HC05
Families the H register is not pushed on the stack during interrupt entry. If
the interrupt service routine modifies the H register or uses the indexed
addressing mode, software should save the H register and then restore it
prior to exiting the routine.
A software interrupt pushes PC onto the stack. A software interrupt does
not push PC – 1, as a hardware interrupt does.
INT1
INT2
demonstrates what happens when two interrupts are pending. If an interrupt
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
Figure 14-10
CLI
LDA
PSHH
PULH
RTI
PSHH
PULH
RTI
#$FF
.
Interrupt Recognition Example
NOTE
NOTE
INT1 INTERRUPT SERVICE ROUTINE
INT2 INTERRUPT SERVICE ROUTINE
BACKGROUND
ROUTINE
Program Exception Control
163